Electric phonograph circuit



J. WEINBERGER ELECTRIC PHONOGRAPH C IRCUI' Filed July 21, 1925 2 sheets-sheet 2 Umm/Eco@ Juuus WEINBERGER @a msm-f l l? ou/uyul PatentedA July JULI'US WEINBERGER, OF NEW monly used with phonographs with radio receiving circuits.

AMERICA,

TES PATENT oFFicE.

YORK, N. Y., ASSIGNOR T0 RADIO CORPORATION 0F A CORPORATION OF DELAWARE.

ELECTRIC PHONOGRAIH CIRCUIT.

Application filed July 21, 1925. Serial' No. 44,986.

invention relates to reproducers coinin connection It has for its object the adaptation, improved operation and simplification of apparatus commonly used with these two types of devices.

For further object it is intended to aid in the manipulation,

tion of tone which is adjustment and modificaderived from a phonograph in a simpler .and more eiiicient manner th an heretofore.

It is well known that an ordinary phonograph is incapable of accurate and minute adjustment by the means furnished with the instrument and particularly so for a person not skilled in the art. nishes means which My device furare simple, readily accessible and easily operated. I accomplish this by use of a tone modifier in the shape of variable inductance, tentiometer located arm or base or any where it can be transformer lor poin a portion of the tone other convenient place reached .and manipulated easily. This modifier acts upon a current which is generated directly from the reproducing device itself.

The reproducing device has an electro-magnetic arrangement which produces currents according to the sound vibrations. that any changes can be seen in this way the control of the output circuit through such a modifier may directly affect any apparatus which is attached to it.

We may consid source of constant of frequencies, th an inductance (th ducer coil).

rlhat is to say,

er such a reprodiicer as a voltage over a wide range is voltage acting through e iiiductance of the reprothe reproducer may be regarded asa generator ofvariable frequency voltage nal inductance.

Further and more s, having a certain interdeinite objects may be observed in connection with the annexed drawings, specific ation and claims.

Fig. 1 of the drawing shows my reproducer, tone arm and support combined with the tone modifier. Fig. 2 ,Shows a @aan of 'the reproducen Figs. '4; to 7 show different methods of y wiring my apparatus.

1 shows the electro-magnetic arrangement for sending electric currents corresponding to the tone according to the motions of needle 9 on the record 15. This needle is held in socket 10 or by any other suitable means.

3 is a pivoted connection to a. rotatable tone arm 16 having a counter-weight 2 mounted on the opposite side from the reproducer 1 in order to counteract some of the weight on the record 15. 16 is free to rotate in a horizontal plane .as shown at 4. 5 is the pedestal for mounting the whole arrangement securely to a base member 18 by means of screws or other devices. In the base portion of 5 is located a controlling means 6 which may be in the form of a variable transformer, potentiometer, variometer,

Current which is generated in the reproducer 1 is carried along the conductor 17 anda into the current varying apparatus 6. Here the conductivity, or the coupling, as the ease may be, is varied according to the setting on the indicator 19 and the resultant current is sent out on the conductor 7 to suitable amplifiers or loud speakers as desired.

8 in Fig. 2 Shows the shape of the permanent magnet which causes a flow of eurrent in the coil 20 as the armature 11 vibrates back and forth between its respective pole pieces 12 and 13 according t-o undulations or variations in the record 15. |The coil 20 is more clearly shown in Fig. 3. 14 is a lieXible mounting piece to allow the armature 11 to vibrate in the proper way.

Fig. 4 indicates my conception of such a reproducer, as a generator, connected to a potentiometer 21 and amplifier 22, 23. By means of this arrangement the amplier may reproducen the current will diminish as -be supplied With voltages of variable intensity, enabling the listener to adjust the volume from his loud speaker 24, to his own satisfaction, without changing needles in the However, the arrangement of Fig. 4 has disadvantages, when we consider the reproducer as an inductive generator: It will vreadily be seen that the current flowing through the potentiometer will be reduced when the inductive reactance of the reproducer 1 becomes greater than the total rcsistance of"the potentiometer 21, and that the' frequency goes up. For example, if the reproducer has an induetance of 1 henry, and the potentiometer a resistance of, say, 5000 ohms total, then the inductive reactance of the reproducer will be 6000 ohms at 1000 cycles, 12.000 ohms at 2000 cycles, and so on, increasing with increasing frequency; so that the current through the potentiometer and therefore the voltage across it will progressively fall off above 1000 cycles. The potentiometer arrangement is therefore a less desirable one for use in controlling the volume of an electro-magnetic reproducer.

more desirable arrangement is shown in Fig. 5. Here a transformer or auto-transformer 25 is used for controlling the voltage` supplied from the reproducer to the input transformer' of the amplifier. It will be seen that the voltage between the reproducer l and auto transformer divides independently of frequency. For example, if the inductance of the reproducer is 1 henry, and the total inductance of the auto transformer is 9 henrys, the auto transformer will take 90% of the voltage generated inside of the reproducer, and take this same percentage at all frequencies. rl'his may then be tapped off to the desired amount by the provision of suitable taps to a. rotating switch 6 or equivalent arrangement.

Another arrangement for accomplishing the same object is shown in Fig. 6. Here taps are provided on the primary side 28 of the amplifier input transformer, This arrangement has the same advantages as the arrangement in Fig. 5, in providing a means of volume control which does not cause loss of high frequencies. 'llhe voltages divideV between the inductance of the reproducer, and the in'ductance of the primary 28 of the transformer. The voltage delivered by the secondary 29 of the transformer is equal to the voltage drop across the primary multiplied by the ratio of turns.

similar arrangement is shown in Fig. 7, except that in this case taps are placed on the secondary side of the amplifier input transformer.

1n the ordinary phonograph reproducing horn, the volume and quality of the tone is oftentimes modified by introducing a Sound absorbing body into the throat of the horn by means of a simple shutter. The disadvantage of this arrangement is that it produces reverberation and undesirable resonance periods from Vsuch stoppage or reflection of the sound waves. The only way of regulating the actual volume of sound produced is by changing the size and .stiffness of the reproducing needle as at 9. This method, too, has its disadvantages which will not be discussed in detail here. It is sufHcient to say, however, that a needle of one particular size produces the best results. 4

With this invention a proper size needle may be always used and a direct control of the sound output without resonance,l undesirable reverberationsor other disagreeabley results is possible.

lt has been found that this apparatus may be installed in the ordinary type of phonograph without much difficulty. The conducting wire 17 can be run through the ordinary tone arm in the space provided for conducting sound.

,'lhus having described my invention, I do not wish to be limited to the exact modification shown but only in so far as it would involve invention to substitute equivalent elements or arrangements of those shown and as indicatedin the following claims.

l claim:

1. ln combination, a variable grooveydevice, means for following variations, a movable armature connected therewith, a coil surrounding the armature, transmission means from the coil, and inductive current controlling means connected to the transmission means for varying` the intensity of electrica] oscillations produced by the coil.

2. In combination, a variable groove device, means for followingvariations, a movable armature connected therewith, a coil surrounding the armature, transmission means from the coil, and inductive current controlling means connected to the transmission means for varying the intensity of electrical oscillations produced by thecoil Whereby a constant voltage ratio exists between the coil and the controlling m-eans irrespective of frequency.

3. In combination, a variable groove device, means for following variations', a movable armature connected therewith, a coil surrounding .the armature, transmission means from the coil, and inductive current controlling means connected to the transmission means having a definite known inductance relative tothe coil forL producing maximum output efficiency therefrom and for varying the intensity of electrical oscillations produced by the coil.

4. 1n combination, a variable groove device, means forl following variations, a movable armature connected therewith, a coi/l surrounding the armature, transmission means from the coil, and inductive current controlling means connected to the transmission means having a definite known inductance relative to the coil for producing maximum out-put efficiency therefrom and for varying the intensity of electrical oscillations produced by the coil, whereby a constant voltage ratio exists between the coil and the controlling means irrespective of frequency.

5. A phonograph pickfup device comprising a needle adapted to be mechanically vihrated, mea-ns including a coil for converting the mechanica-l vibrations into electrical oscillations, a transmission line from said coil, and inductive cm'icnt controlling means connected to said transmission line 'for varying the intensity of the electrical oscillations produced in said coil.

' J'UIIUS WENBERGER. 

